Transparent plastic materials such as eyeglass lenses, television screen face plates and the protective coatings on photographic prints often are quite soft and are subject to becoming dull and hazy due to scratching and abrasion during use. Polycarbonate eyeglass lenses, for example, are strong and shatter resistant but also are relatively soft and susceptible to scratching. Television screen face plates similarly are made of flexible, shatter resistant plastic materials such as polycarbonate and poly (methylmethacrylate), and these also can be scratched or abraded.
Various coatings have been proposed for eyeglasses and other transparent plastic materials to reduce their propensity to become scratched and abraded. One such composition is shown in U.S. Pat. No. 4,378,250 (Treadway, et al.) granted Mar. 29, 1983. Other coatings are shown in U.S. Pat. Nos. 5,367,019 (Sawara), 4,855,180 (Kawamura), 4,895,767 (Mori et al.) and 4,719,146 (Hohage et al.) Besides being abrasion resistant, coatings for eyeglass lenses should also be capable of being tinted by treatment with a dye which becomes incorporated in the coating. As a general observation, the tintability of a coating tends to decrease as its hardness and scratch resistance increases, and vice-versa.
Harasta, et al. U.S. Pat. No. 4,426,431 discusses a coating composition referred to as a "hybrid " system because it employs a solution, in a solvent such as propylene carbonate, an epoxy compound and a cationic initiator for it, and an acrylic compound and a free radical initiator for it. In general, coating compositions suitable for use in forming protective transparent coatings on eyeglass lenses and the like are provided in solution in a volatile solvent, the solvent serving as a low viscosity vehicle to enable the coating composition to be uniformly spread upon a surface and to accept dye treatments. The solvents that are employed are for the most part organic, and must be used and disposed of carefully.
Perkins et al. U.S. Pat. No. 5,221,560 describes a coating composition containing a polyfunctional, polymerizable non-acrylate functional ether, a radiation-sensitive initiator, and colloidal silica in an amount providing at least 25% by weight of the total solids of the composition, the silica being reacted with a small amount of a hydrolyzed acryloxy-functional or glycidoxy-functional silane.
It would be desirable to provide a coating composition that is capable of forming coatings having both excellent abrasion resistance and dye acceptance.